Vehicle track support

ABSTRACT

Vehicle track support means comprising laterally spaced rollers underlying the return run of the track to absorb vertical track forces. Wear plates are disposed between the rollers to engage side surfaces of the track teeth, thereby preventing lateral dislocation of the track. In a preferred arrangement the wear plates are readily replaced without disturbing the rollers, and vice versa.

United States Patent [191 Turkiewicz et al. v

[54] VEHICLE TRACK SUPPORT [75] Inventors: Richard R. Turkiewicz, Warren;

Anthony J. Volino, Detroit, both of Mich.

[73] Assignee: The United States of America as represented by the Secretary of the Army, Washington, DC.

[22] Filed: Oct. 3, 1974 [2]] Appl. No.: 511,875

[52] US. Cl 305/56; 305/28 [51] Int. Cl. B62D 55/20 [58] Field of Search 305/l6, l7, i8, 25, 28,

[56] References Cited UNITED STATES PATENTS 3,606,497 9/ l 971 Gilles 305/56 [ll] 3,929,385 Dec. 30, 1975 FOREIGN PATENTS OR APPLICATIONS 674,516 6/ I952 United Kingdom 305/56 Primary Examiner-Philip Goodman Attorney, Agent, or Firm-John E. McRae; Peter A. Taucher; Robert P. Gibson [5 7] ABSTRACT Vehicle track support means comprising laterally spaced rollers underlying the return run of the track to absorb vertical track forces. Wear plates are disposed between the rollers to engage side surfaces of the track teeth, thereby preventing lateral dislocation of the track. In a preferred arrangement the wear plates are readily replaced without disturbing the rollers, and vice versa.

10 Claims, 6 Drawing Figures US. Patent Dec. 30, 1975 Sheetlof3 3,929,385

prior an Fig US. Patent Dec. 30, 1975 Sheet 2 of3 3,929,385

//A w n f u N i w. x fi fl w m x A A w a 4 5 w, y a 2 n f w y mo y z US. Patent Dec. 30, 1975 Sheet 3 of 3 VEHICLE TRACK SUPPORT The invention described herein may be manufactured, used, and licensed by or for the Government for BACKGROUND AND SUMMARY OF THE INVENTION Tracked vehicles sometimes are provided with grooved support rollers underlying the return run of the track. The track teeth pass through the grooves in the rollers, thereby guiding the track against lateral dislocation or misalignment. The track teeth may be approximately 3% inches in length, necessitating a slightly greater roller groove depth. In practice the rollers have diameters on the order of l2 inches to accommodate the necessary groove depth plus radial wall area at the roller centerline.

Large diameter rollers tend to undesirably limit upward travel of the road wheels, thereby setting artificial limits on the suspension system. The present invention proposes an upper roller design wherein the grooved roller is replaced by two laterally spaced rollers. The intervening space between the two rollers is left vacant down to a point at least below the roller centerline, such that the track teeth can penetrate or intersect the roller centerline without striking the rollers or roller supports. Roller diameter can be reduced from the present twelve inches to a much smaller value, e.g. 6 inches. The smaller rollers can be placed nearer the upper run of the track, thereby posing less of an obstruction to upward travel of the road wheels.

THE DRAWINGS FIGS. 1 and 1A are fragmentary side elevational comparison views of tracked vehicles using conventional return rollers and the proposed return rollers.

FIG. 2 is a sectional view taken through a proposed roller assembly.

FIG. 3 is a sectional view taken on line 3-3 in FIG. 2.

FIG. 4 is taken through a conventional roller on the same line as FIG. 2.

FIG. 5 is a sectional view taken through a variant of the FIG. 2 design.

FIGS. I AND IA FIG. I shows in side elevation a portion of a vehicle [0 having a road wheel 12 rotatably carried on an axle 14 attached to a swingable road arm 16. The road arm includes a barrel 18 having a rotary fit on a shaft or hub structure 20 carried by the vehicle hull. A torsion bar, coil spring or other resilient cushioning device (not shown) is ordinarily associated with each road arm to provide the necessary suspension force. Each road wheel bears on a conventional endless track 22 having centrally located teeth 24 adapted to interfit with the road wheels to prevent the track from wandering off course. Each road wheel is grooved to permit the track teeth to freely pass through the wheel outline.

An illustrative vehicle might have six road wheels at each side of the hull, plus one drive wheel at the front (or the rear), one idler wheel at the rear (or front), and two return rollers underlying the upper return of the track. Road wheel 12 (and the other road wheels) may be about 24 inches in diameter. Ordinarily the road wheels are relatively closely spaced, e.g. on 28 inch centers, to provide proper track guidance. Such close positionment of the road wheels makes it difficult to locate the overhead return rollers where they will not interfere with upward travel of the road wheels, as when the vehicle is travelling over bumpy or uneven terrain. As seen in FIG. 1, the conventional return roller 26 is located above and slightly offset from the road wheel 12. The diameter of wheel 26 is sufficiently large to effectively limit uptravel of the road wheel to arcuate distance 27 (about 25 radial degrees).

FIG. IA illustrates the FIG. 1 vehicle equipped with a smaller return roller assembly 28 proposed under the present invention. The smaller return roller assembly permits larger travel of the road wheel, as designated by arcuate distance 30.

FIGS. 2 AND 3 FIGS. 2 and 3 illustrate certain details of the roller assembly 28 shown schematically in FIG. IA. The roller assembly comprises two independently rotatable rollers 32 and 34 mounted on stub shafts 36 and 38 projecting in opposite directions from an upwardly facing yoke 40. Conventional anti-friction bearings 42 and seals 44 are interposed between the stub shafts and rollers. Each roller is provided with a cover 46 equipped with a viewing window 48 and a lubricant supply opening (closed by screw 47). An oil port or passage 49 is drilled through yoke 40 to communicate one bearing area with the other. This enables both bearing areas to be filled with oil through the supply opening that happens to be located at the outer exposed surface of the assembly.

Yoke 40 is suitably affixed, as by welding, to a subjacent platform 50 that extends rightwardly (FIG. 2) to a non-illustrated connection with the hull of the vehicle; members 40 and 50 cooperatively define a single bracket means effective to mount rollers 32, 34 and wear plates 52.

The return run of track 22 moves over the upper surfaces of rollers 32 and 34 so that the rollers absorb the vertical track forces. The teeth 24 of the track project downwardly into the central space defined by yoke 40; bight surface 41 of the yoke is located below the roller centerline 61, thereby forming a deep passage for teeth 24. Wear plates or shoes 52 are releasably secured to the facing surfaces 54 of the yoke, as by means of light captive bolts 56 (four for each shoe). One of the bolts is shown in elevation in FIG. 2; the bolt spacing is shown in FIG. 3. Each bolt has an exposed head 58 located on the outer face of a web 60 formed integrally with yoke 40; the bolts can therefore be unthreaded from shoes 52 sufficiently to permit removal of a worn shoe and replacement with a new shoe.

Shoes or plates 52 are located inboard from the rollers alongside the path taken by track teeth 24. The plates therefore contact the side surfaces of the teeth before the teeth have begun to wander excessively from the designated plane of movement; lateral track forces are absorbed by the wear plates.

In general, rollers 32, 34 and wear plates 52 absorb vertical and lateral track forces to prevent track whipping and dancing that can wear or damage the track or adjacent structures. Usually two roller assemblies 28 are provided at longitudingally spaced points along each side of the hull. The relatively small diameters of the rollers permits a wider choice of locations than is possible when large diameter rollers 26 (FIG. I) are used.

. they abut together. The rectangular plates 52 used in FIG. 4

FIG. 4 is a semi-schematic view of the conventional roller assembly 26 depicted in FIG. I. As shown in FIG. 4, the single grooved roller 26 is supported on a stationary shaft 62 suitably anchored to the vehicle hull'by mounting means, not shown. Bearings 64 are interposed between the shaft and roller. A deep groove 66 is provided in the roller surface to accommodate the track teeth 24. Lateral dislocation of the track is prevented or controlled by means of annular. wear plates 68 suitably bolted or riveted to the groove 66 surfaces.

FEATURES OF THE INVENTION Comparing the structures olFIGS. 2 and 4, it will be seen that in one case the track tooth 24 extends to a point below the roller centerline (FIG. 2), whereas in the other case the track tooth extends downwardly only partway toward the roller centerline (FIG. 4). The FIG. 2 structure uses two spaced-apart rollers, thereby enabling yoke 40 to form a central unobstructed space for accepting the track teeth; the FIG. 4 roller obstructs the space that could otherwise be used to accept the track teeth. Therefore the FIG. 4 roller must have a diameter considerably more than twice the depth of teeth 24 whereas the FIG. 2 rollers can have diameters considerably less than twice the tooth 24 depth, as determined primarily by the radial space required for bearings. In practice the FIG. 2 roller can be approximately 6 inches in diameter, whereas the FIG. 4 roller must have a diameter of approximately l2 inches. The larger diameter roller obstructs road wheel travel, as explained previously in connection with the description of FIGS. I and IA.

It will be noted that the vertical centerlines of the rollers in FIG. 2 are spaced apart by a relatively large distance A, whereas the corresponding roller surfaces in the FIG. 4 structure are spaced apart by a relatively small distance B. The wide spacing A gives the rollers a wider support stance for the track, hence better resistance against vibration in the tilting planeand therefore possibly lesser stress on the roller surfaces. The wider stance is due to the use of two independent rollers (FIG. 2). Economics dictate against providing wide stance" support with a single roller (FIG. 4), especially if the roller has a large diameter. The use of two rollers also is advantageous in effecting a redundancy that permits the assembly to retain its track support function in event of failure of one roller.

It will be seen that the FIG. 2 wear plates 52 are essentially flat plate structures (although the leading and trailing edges are preferably bevelled for preventing any hang up of the track). The flat plates can be fabricated and heat treated at lesser cost than the curved plates 68 shown in FIG. 4. Each curved plate 68 has a slight conical surface contour to properly seat on the roller surface; during heat treatment warpage can sometimes occur, thereby disturbing the contour originally designed into the plate.

As seen in FIG. 4, each plate 68 is a complete annulus. Actually each annular plate must be constructed as two or more segmental plates in order to permit installation on the roller; Le. a single annulus could not pass over the roller outside diameter to effect installation or removal. The use of a plurality of segmental plates somewhat complicates the plate fabrication and plate mounting process. Additionally the installed plates can conceeivably form a track-obstructing shoulder where the FIG. 2 structure avoid some of thefabrication and mounting problems associated with the FIG. 4 plates.

In the field the FIG. 2 plates 52 should prove easier to remove and replace, since the mounting bolts 56 can be threaded and unthreaded without disturbing the rollers. During usage the rubber tread areas on the rollers can be defonned slightly to overlap or mask the wear plates 68 (FIG. 4), thereby making plate replacement difficult It is believed that in many cases the field personnel tend to replace theentire roller (FIG. 4) even though all that is required is replacement of one or both of the wear plates. With the FIG. 2 arrangement replacement of one or both rollers has no effect on the wear plates; therefore the technician is not prone to replace a roller when all that is required is a new wear plate.

It will also be seen that the wear plates shown in FIG. 2 and 3 provide flat wear surfaces of extensive length in the direction of tooth 24 movement. Each plate is adapted to engage the entire side surface of the tooth to provide low unit area forces. The conical nature of the FIG. 4 plates 68 means that those plates have only line contact with the tooth side faces, hence higher unit area forces and frictional wear; wear plates-68 only contact the tooth side faces on a vertical line at the l2 o'clock position.

Each wear plate 52 has a length (FIG. 3) greater than the centerline spacing C of the teeth 24. Therefore at least one tooth is always under control by the plates; before one tooth leaves the control cone another tooth enters the zone. In the FIG. 4 arrangement it is of course possible to have two teeth within groove 66 at any one instant; however the annular wear plate only provides guide action when a tooth is at the 12 o'clock position (i.e. directly over the wheel centerline). Therefore the guiding is intermittent, not continuous as in the flat plate arrangement shown in FIGS. 2 and 3.

Plates 52 are shown in FIG. 2 as somewhat thicker than the annular plates 68 used in the FIG. 4 structure. The increased thickness, and consequent increased life, is possible because of the simpler fabrication techniques that can be used.

As previously noted, plates 52 are separate from the rollers. Disposition of plates 52 remote from rollers 32 and 34 is advantageous in an operational sense because the wear plates distribute lateral loads onto the rigid yoke surface rather than the roller bearings. The bearings 42 are required to handle only radial loads (vertical forces). The bearings should therefore have a longer service life. This is particularly important in some vehicles having an "unbalanced" wear situation, dueto any one of numerous imprecisions such as track manufacturing tolerances, slight axle misdirection, hull dimension deviations, etc. Inmany vehicles such im precisions result in slight pulling" of one or both tracks to the right or left; i.e. the track teeth want to move laterally or at a slight angle to the wear plates (68 or 52). When the wear plates are rigidly mounted on fixed support structure, as in FIG. 2, the abnormal wear pattern is absorbed without loading-up the roller bearings in the axial (thrust) direction.

FIG. 5

This Fig. illustrates a possible structural variation having some of the advantages of the FIG. 2 structure. Thus, the FIG. 5 assembly employs two independently rotatable rollers 32' and 34' laterally spaced apart to provide a central vacant space 53 that accommodates S the track teeth 24. The track teeth can intersect the roller axis 61, thereby permitting the use of small diameter rollers having the non-obstruct" qualities of the roller means 28 shown in FIG. 1.

The rollers in the FIG. construction are rotatably mounted on aligned stub shafts 36' and 38' extending inwardly from pedestals 55 suitably bolted to a platform 50' that is adapted to be attached to the hull of the vehicle, not shown.

The FIG. 5 construction uses annular wear plates 69 bolted or otherwise removably secured to the rollers. Therefore the structure lacks some of the described advantages of the FIG. 2 structure. However, since the rollers are independent, and the central space 53 is completely vacant, the wear plates can each be formed as a single one piece annulus because the annulus does not have to slip over the outside diameter of the associated roller; the annulus can be installed with a straight axial movement. Replacement of a worn wear plate 69 would probably be accomplished after first unbolting the associated pedestal 55 from platform 50' to permit manual manipulation of the respective roller subassembly.

As previously noted, the structure of FIG. 2 represents a preferred embodiment of the invention. FIG. 5 represents a less preferred arrangement. Some further variations may be practiced within the scope of the invention as recited in the attached claims.

We wish it to be understood that we do not desire to be limited to the exact details of construction shown and described, for obvious modifications will occur to a person skilled in the art.

We claim:

1. In a tracked vehicle: two independently rotatable rollers underlying the return run of the track to absorb vertical forces; said rollers being axially aligned with one another on opposite sides of the path taken by the teeth that project downwardly from the track; each roller having a radius that is less than the track tooth height, whereby the tooth path intersects the roller centerline; the central space between the rollers being 6 unobstructed for a sufficient vertical distance to permit passage of the track teeth therethrough.

2. In the vehicle of claim I: wear plates located inboard from the rollers to engage side surfaces of the track teeth, thereby retarding lateral dislocation of the track.

3. In the vehicle of claim 2: said rollers being supported on a bracket structure that includes an upwardly facing yoke located between the rollers, the facing areas of the yoke constituting mounting surfaces for the wear plates.

4. In the vehicle of claim 2: said wear plates having horizontal length dimensions greater than the track tooth spacing, whereby one tooth enters the plate zone before departure of the preceding tooth.

5. In a tracked vehicle: roller means underlying the return run of the track to absorb vertical track forces; shoe means separate from the roller means for contacting side surfaces of the track teeth to thereby absorb lateral track forces; and single bracket means mounting the roller means and shoe means on the vehicle.

6. In the vehicle of claim 5: said shoe means comprising wear plates releasably joined to the bracket means in locations alongside the path taken by the track teeth.

7. In the vehicle of claim 5: said roller means comprising two independently rotatable rollers located outboard from the track tooth plane.

8. In the vehicle of claim 5: said roller means comprising two independently rotatable rollers located outboard from the track tooth path; said shoe means comprising wear plates located inboard from the rollers alongside the tooth path.

9. In the vehicle of claim 8: the aforementioned bracket means comprising a yoke located between the rollers to support the wear plates, said yoke having outwardly projecting stub shafts for supporting the rollers.

10. In the vehicle of claim 9: said yoke having its bight surface located below the roller centerline, whereby the yoke defines a track tooth passage at least as deep as the roller radius.

i II i 1 i 

1. In a tracked vehicle: two independently rotatable rollers underlying the return run of the track to absorb vertical forces; said rollers being axially aligned with one another on opposite sides of the path taken by the teeth that project downwardly from the track; each roller having a radius that is less than the track tooth height, whereby the tooth path intersects the roller centerline; the central space between the rollers being unobstructed for a sufficient vertical distance to permit passage of the track teeth therethrough.
 2. In the vehicle of claim 1: wear plates located inboard from the rollers to engage side surfaces of the track teeth, thereby retarding lateral dislocation of the track.
 3. In the vehicle of claim 2: said rollers being supported on a bracket structure that includes an upwardly facing yoke located between the rollers, the facing areas of the yoke constituting mounting surfaces for the wear plates.
 4. In the vehicle of claim 2: said wear plates having horizontal length dimensions greater than the track tooth spacing, whereby one tooth enters the plate zone before departure of the preceding tooth.
 5. In a tracked vehicle: roller means underlying the return run of the track to absorb vertical track forces; shoe means separate from the roller means for contacting side surfaces of the track teeth to thereby absorb lateral track forces; and single bracket means mounting the roller means and shoe means on the vehicle.
 6. In the vehicle of claim 5: said shoe means comprising wear plates releasably joined to the bracket means in locations alongside the path taken by the track teeth.
 7. In the vehicle of claim 5: said roller means comprising two independently rotatable rollers located outboard from the track tooth plane.
 8. In the vehicle of claim 5: said roller means comprising two independently rotatable rollers located outboard from the track tooth path; said shoe means comprising wear plates located inboard from the rollers alongside the tooth path.
 9. In the vehicle of claim 8: the aforementioned bracket means comprising a yoke located between the rollers to support the wear plates, said yoke having outwardly projecting stub shafts for supporting the rollers.
 10. In the vehicle of claim 9: said yoke having its bight surface located below the roller centerline, whereby the yoke defines a track tooth passage at least as deep as the roller radius. 